Surface acoustic wave excitation device

• US 7,375,454 B2
• Filed: 04/17/2007
• Issued: 05/20/2008
• Est. Priority Date: 10/19/2004
• Status: Expired due to Fees

• Current Assignee: National University Corporation Saitama University
• Original Assignee: National University Corporation Saitama University
• Inventors: Takasaki, Masaya
• Primary Examiner(s): Dougherty; Thomas M
• Application Number:
  US11/785,290
• Publication Number:
  US 20070247019A1
• Time in Patent Office: 399 Days
• Field of Search: 310/313.R, 310/344, 310/354, 310/355
• US Class Current: 310/313.00R
• CPC Class Codes: G06F 3/016 Input arrangements with force or tactile feedback as computer generated output to the user
• CPC Class Codes: H02N 2/08 using travelling waves , i.e. Rayleigh surface waves
• CPC Class Codes: H03H 9/02976 with semiconductor devices
• CPC Class Codes: H03K 2217/96011 with propagation, SAW or BAW
• CPC Class Codes: H03K 2217/96062 with tactile or haptic feedback

Abstract

[Problems]

To provide a surface acoustic wave excitation device for efficiently exciting the surface acoustic wave on the surface of a material such as glass having free size and shape for making mechanical vibration available.

[Means to Solve the Problems]

The surface acoustic wave excitation device according to the present invention comprises a non-piezoelectric member 30 such as glass, a piezoelectric member 20, interdigital transducers 11 interposed between the non-piezoelectric member 30 and the piezoelectric member 20, and pre-pressurizing means 42 for pressing the piezoelectric member 20 onto the non-piezoelectric member 30 by way of the interdigital transducers. Alternating voltage is applied to the interdigital transducers 11 for exciting the surface acoustic wave on the non-piezoelectric member 30. Standing waves are generated in the piezoelectric member 20 by applying alternating voltage to the interdigital transducers 11, thereby allowing alternating strains to propagate to the non-piezoelectric member 30 such as a glass substrate or the like by way of the electrodes 11 and exciting the surface acoustic wave for making mechanical vibration of the non-piezoelectric member 30 available.

Claims

1. A surface acoustic wave excitation device comprising a non-piezoelectric member made of a glass, a piezoelectric member, interdigital transducers constituting a pair of the finger electrodes interposed between the non-piezoelectric member and the piezoelectric member, and pre-pressurizing means for applying pressure onto the piezoelectric member against the non-piezoelectric member by way of the interdigital transducers, wherein the length of the piezoelectric member in the perpendicular direction to the finger electrodes of the interdigital transducers is set to integer times of the ½

wavelength of the wave propagating on the piezoelectric member to cause standing waves of an acoustic wave on the piezoelectric member when alternating voltage is applied to the interdigital transducers, thereby exciting the surface acoustic wave on the non-piezoelectric member.

2. A surface acoustic wave excitation device of claim 1, wherein the pitch of the adjacent finger electrodes is set to ½

wavelength of the wave propagating the non-piezoelectric member.

3. A surface acoustic wave excitation device of claim 1, wherein grooves for enhancing acoustic coupling between the piezoelectric member and the non-piezoelectric member are provided in parallel with the finger electrodes in the surface of the piezoelectric member contacting the interdigital transducers but at locations not contacting the finger electrodes.

4. A surface acoustic wave excitation device of claim 3, wherein projections of the piezoelectric member that contact with the finger electrodes expand or contract in the vertical direction with respect to the finger electrodes in resonance with the frequency of the surface acoustic wave exciting the non-piezoelectric member.

5. A surface acoustic wave excitation device of claim 1, wherein the pre-pressurizing means presses the piezoelectric member onto the non-piezoelectric member by utilizing vacuum sucking.

6. A surface acoustic wave excitation device of claim 5, a soft cover is provided to cover the piezoelectric member and having a skirt portion for closely attaching the non-piezoelectric member, and inside of the soft cover is evacuated for pressing the piezoelectric member onto the non-piezoelectric member.

7. A surface acoustic wave excitation device of claim 5, wherein a vacuum space is provided between the piezoelectric member and the non-piezoelectric member and the space is air-tight sealed with the parallel finger electrodes and the adhesive disposed on the side of the interdigital transducers in the perpendicular direction to the finger electrodes.